** Carb Grabbing at Start **

Discussion in '2-Stroke Engines' started by vintage97302, Apr 5, 2011.

  1. vintage97302

    vintage97302 New Member

    First, I have looked through the topics on here searching for this exact issue and was unable to locate an answer, so here goes: My bike has been done for less than a week now. I am running the typical 80/66cc Grubee Skyhawk. I replaced the Chinese spark plug that came with the kit with a NGK one.

    My problem is that the first time that I try to start the bike ( only when it is a cold start ie starting it the next day ) I have the choke set right, the gas is on...I get good peddling speed, let go of the clutch and give it some gas...it begins to chug, now not that the motor is having problems kind of chug, but that the clutch is grabbing. Then it dies and I end up wearing myself out repeating this process over and over again until finally it lights up and goes.

    After I can finally get it to go and I ride it for 5 - 10 min I can shut it off, leave it for even 30 min, jump back on it, peddle for a few feet, pop the clutch and it starts right up, No clutch grabbing. I am not sure why when the engine is real cold that the clutch seems to grab...Anyone have any suggestions or advice??

    Thanks, Eric

  2. motorpsycho

    motorpsycho Active Member

    it's because you're trying to start a cold engine. letting it sit for 30 minutes does not let the engine cool all the way back down, there will still be some heat in it which will help it re-start much easier.

    it's not that the clutch is grabbing when cold, it's that it's harder for the engine to ignite the cold air-fuel mixture with a cold cylinder and piston.
    you will see this problem go away when the outside temps get alot warmer.
  3. vintage97302

    vintage97302 New Member

    Thanks for the 411. I live in Oregon and right now we don't get many days where the temp reaches over 55 degrees. I just always thought that it should be able to just start every time. Just the perils of being a newbie.:evilgrin:
  4. MikeJ

    MikeJ Member

    Some guys (myself included) have preheated their engine cylinders with hair dryers. It takes a few minutes; probably less than the time and effort you have been putting into starting. If you try this, let us know if this works for you. Do not use open flames like propane torches.
  5. vintage97302

    vintage97302 New Member

    Wow, hair dryers. I never would have even thought of that. I thought that the problem might be more serious than that the engine is just cold. Thanks for the advice and tip. Too bad they couldn't make it so we could plug the engine in, like a head bolt heater *lol*
  6. MikeJ

    MikeJ Member

    Well, if you want to get fancy.... Check with the local auto parts store and ask for a car battery warmer. I had to use them to start a diesel engine on cold mornings. It is literally an electric blanket for car batteries. You plug it in overnight. Wrap that around your cylinder head. It could be used for other warming purposes as well, I suppose.
  7. vintage97302

    vintage97302 New Member

    I rode the bike today for over an hour today. It did the grabbing/pulling thing, took it as it is cold...it just catches then wants to fire up...then, it does great. I let it cool for about 15 min...got on it, did the same exact thing. Someone also told me that my problem also it the 16:1 break in oil to gas ratio as right now there is too much oil in the gas. I have no idea. It bothered me when it did the same thing 15 min after having ran for an hour. I can tell you it is starting to get REAL annoying.
  8. motorpsycho

    motorpsycho Active Member

    it kind of sounds like you are trying to describe a surge. when you say "grabbing /pulling" do you mean that the engine pulls and then the clutch slips (engine revs high wihtout pulling the bike) ?
    or are you trying to say that when you ride, the bike feels like it's pulling back & forth...surging?
    16:1 is too much oil, if you are on the break in, you can knock it down to 20:1. it will still be rich, but it will run better.
    I have found that after break in, 32:1 seems to be a good ratio for me.
    I have even ran one of my bikes ta 40:1 a few times and it has a tiny bit more power....nothing major tho.
    32:1 is a safe gas / oil ratio in my opinion.
  9. Skyliner70cc

    Skyliner70cc Active Member

    32:1 is what you need at breakin and afterwards. No need for super oil rich mixture which makes starting that much difficult.
  10. vintage97302

    vintage97302 New Member

    When I say that it is " grabbing or pulling " it is when I get it going I pop the clutch and it just seems like the clutch isn't making the engine turn over it just goes " chug, chug, chug "...like it is trying to engage. I peddle it again pop the clutch again and gradually give it gas and it catches up to speed then fires up.

    The oil to gas ratio that I am using is the 16:1 ratio. I get so darn confused what the actual ratio should be. I read other topics on this forum and the other MB forum and everyone has a different opinion on what that ratio should be: Some say that I need the 16:1 for the first gallon as I am trying to break in the engine with as little ignition combustion as possible and also with that high oil mixture, it seats the gaskets; Then some say that you never go above 20:1 and that if you do, you can blow your engine...

    This ratio topic is kind of an odd one...like what to do with the " white wire " that comes out of the engine. All I know, concerning this issue, is that I want to peddle a few feet, pop the clutch and have the sucker fire...THE FIRST TIME. I see videos all the time where this happens.

    Thanks guys for all of your advice and tips...they are helping me greatly.

    Last edited: Apr 6, 2011
  11. HeadSmess

    HeadSmess Well-Known Member

    ok, defintions needed...grabbing; a sudden engagement, snatch... slipping; not engaging...

    you have slippage.

    a new engine...hmmmms.... welll... could just be oil on the clutch plate...clean it :) or its a deeper more fundamental problem! such as the cables too tight? non? move on... time to possibly dismantle something :eek:

    the clutch operates with a spring n stuff, and in behind the clutch plate, theres a bearing, with a bush and a nut and so forth...sometimes these protrude slightly too far due to lousy tolerancing, and the clutch plate cant move in far enough, hence it slips on the lil runbber friction pads, it never really engages, and it can never be fixed...

    unless you grind the bush/nut/thread back slightly :) only 1/16 or so!
  12. motorpsycho

    motorpsycho Active Member

    yes, the oil/gas ratio will always be a huge debate. for me, 32:1 works and that's what i'm sticking to. I personally have never seen or heard of a 2 stroke engine "blowing" by running the wrong oil/ gas ratio. I have seen pistons lock up tho from lack of oil in the gas.

    with a high oil/gas ratios (like 20:1) it's not to seat the gaskets, but to seat the piston rings. Gaskets are to keep oil inside the engine, and if you were tryign to seat the gaskets with oil, it would be leaking oil all over the place.

    I don't knwo what to tell you, but i think headsmess is right...you may have a clutch problem.
    seriously tho, getting one of these engines to run and go shoudl not be this difficult.....I think you may have gotten one that was built at 4:45 on a friday evening.
  13. vintage97302

    vintage97302 New Member

    I think you guys are right. I do think that it is the clutch, so did the guy to built the bike for me. There is a guy in our motorized bike club here in town that has had the same exact problem...he is out of town for a week or so...therefore I was trying to find out the solution on my own.

    It runs great once I have it up and running. Pulls me right down the road very, very quickly and I am 285 pounds. It doesn't die on me anytime unless I hit the kill switch. I just think that the clutch needs to be adjusted or do some " grinding ". I can tell you this, since I changed the park plug from the stock Chinese plug to a NGK B6HS and then put in the new ethanol free gas/Lucas 2 Stroke oil mixture in...it does take less to get it started.

    My funds for gas and oil are limited right now...very limited, so I have to burn through the gallon of 16:1 mixture before I can move up. Thanks to everyone for your advice. I will let you know if and when it gets right...and I will pass on what I did to correct it...if anything.
  14. motorpsycho

    motorpsycho Active Member

    one thing i forgot to ask you...does your carb have the primer button on the top of the float bowl?
    if so, are you pushing it in every time you try to start the engine? how many times do you push it? you could be pushing too much gas into the engine which will actually hydrolock the piston and the clutch will just slip no matter how good it is adjusted.
    if you are using the primer button, try starting it a few times without using it and see what happens. On my 66 c.c. with the primer button on the carb, all i need to do is push the primer button once to get the engine to start when cold.
    I found that if i pushed the primer button 2-3-4 times, the clutch will slip when i try to start the engine and the engine will not turn over. (coasting my bike down the driveway and popping the clutch).
    Last edited: Apr 8, 2011
  15. vintage97302

    vintage97302 New Member

    It does. To be honest I push it once at the beginning some times, not all the time. It has gotten better, but today is was around 65 degrees and it still did it. When I peddle it and pop the clutch...it is like it runs very low, then putters off and stops. I repeat the process all over again, pop the clutch then it runs low then POW!!! it fires up. I run it for a while and then engage the clutch fully and it is good from then on.

    It is bizarre I can tell you that.
  16. motorpsycho

    motorpsycho Active Member

    this one has me stumped
  17. vintage97302

    vintage97302 New Member

    It is just annoying is all. I have really built up my leg muscles from all the hard peddling I have been doing. It doesn't take away from the enjoyment I have been having this last week of riding.

    We shall see what I come up with. Thanks for all your help and suggestions and advice. If I get it fixed I will make sure to post what it was =)
  18. Rayde

    Rayde New Member

    You could check the grounds, and all electrical connections to the CDI, magneto, plug, etc.

    If you're getting a bad ground, it make take a few revs for it to finally ground to the frame, and the CDI to kick in and give you power.

    I'm a welder, so good grounds are always on my mind. :)
  19. TucsonDIrect

    TucsonDIrect Member

    Ok keep it simple, use your first tank of gas for the breakin period,
    Then JUST follow what your supplier recconmends, if you live in a colder area you can reduce the oil a little, if you live in a hotter climate like tucson give it a little more oil to help cool the engine and keep things lubed,

    if you ever do endup overheating and seixing your engine, Immediately turn the engine over a couple of times, and you should be ok, best to let it run for awhile and just let it cool down on its own. And not much harm done
  20. vintage97302

    vintage97302 New Member

    It stopped doing it...no adjusting, nothing. It has warmed up here a bit and I switched from the break in 16:1 ratio to a 20:1 ratio...no problems!!! All is good. Chalk this one up for an X-Files episode...quite weird...just wanted to update everyone on it.